/**
 * @author jianshan@byai.com
 * @date 2021/3/5 3:17 PM
 * describe:
 */
public class DistinguishCardType {


    public static void main(String[] args) {

    }


    private static String distinguishCardType(String cardNumber){
        String number = cardNumber;



        if (number == null || number.trim().length() <= 0) {
            return null;
        }
        return null;
    }

}
